Management of early blight of potato using bio control agents and plant extracts

Abstract

The early blight of potato is mainly controlled by using chemical fungicides but chemical fungicides have got some adverse effect on environment as well as human beings. Keeping this in mind an experiment was conducted to test the efficacy of four plant extracts (tea, garlic, onion and neem leaf extract) and four bio-control agents (Trichoderma viride, Pseudomonas fluorescence, Streptomyces graseoviridis and Bacillus substilis) in controlling early blight of potato under field and in in vitro condition. These antifungal compounds were applied 3 times at 7days interval after first appearance of the disease in the field. Among the bio control agents T. viride was found highly effective in per cent disease reduction (52.39%) of disease over control treatment. The tuber yield (25.51 t/ ha.) was also highest in this treatment compared to control treatment (19.53 t/ha). This was followed by treatment T₂ i.e. P. fluorescens where per cent incidence and intensity of disease were (65.00%) and (19.10%) respectively with 38.97% reduction of disease over control with tuber yield 23.65 t/ha. It was followed by S. graseoviridis where per cent incidence and intensity of disease were (68.00%) and (22.90%) respectively with 26.30% reduction of disease over control with tuber yield 21.07 t/ha. Among plant extracts, only neem leaf extract exhibited per cent reduction of disease (33.18%) over control treatment in field condition and inhibition of radial growth (59.85%) and spore germination (81.95%) in in vitro condition. Therefore both T. viride and neem can be used for managing the early blight of potato.